Survivalist Pro
Survivalist Pro
Photo: Polina Tankilevitch
Physiological definitions of life are popular. Life is defined as any system capable of performing functions such as eating, metabolizing, excreting, breathing, moving, growing, reproducing, and responding to external stimuli.
The first commercial video game console was the Magnavox Odyssey, developed by Ralph H. Baer and first released commercially in 1972. It was...
Read More »
To date, 13 women have been chosen for Special Warfare Combatant-Craft Crewman training, with one completing the course and becoming the Navy's...
Read More »
How To Live Off The Land? 31 Things (2023) You Should Know Find the right parcel of land. You can't live off the land unless you have the right...
Read More »
11 days and 25 minutes The longest time a human being has gone without sleep is 11 days and 25 minutes. The world record was set by … American...
Read More »Much is known about life from points of view reflected in the various biological, or “life,” sciences. These include anatomy (the study of form at the visible level), ultrastructure (the study of form at the microscopic level), physiology (the study of function), molecular biology and biochemistry (the study of form and function at chemical levels), ecology (the study of the relations of organisms with their environments), taxonomy (the naming, identifying, and classifying of organisms), ethology (the study of animal behaviour), and sociobiology (the study of social behaviour). Specific sciences that participate in the study of life focus more narrowly on certain taxa or levels of observation—e.g., botany (the study of plants), lichenology (the study of lichens, leafy or crusty individuals composed of permanent associations between algae or photosynthetic bacteria and fungi), herpetology (the study of amphibians and reptiles), microbiology (the study of bacteria, yeast, and other unicellular fungi, archaea, protists, viruses), zoology (the study of marine and land animals), and cytology (the study of cells). Although the scientists, technicians, and others who participate in studies of life easily distinguish living matter from inert or dead matter, none can give a completely inclusive, concise definition of life itself. Part of the problem is that the core properties of life—growth, change, reproduction, active resistance to external perturbation, and evolution—involve transformation or the capacity for transformation. Living processes are thus antithetical to a desire for tidy classification or final definition. To take one example, the number of chemical elements involved with life has increased with time; an exhaustive list of the material constituents of life would therefore be premature. Nonetheless, most scientists implicitly use one or more of the metabolic, physiological, biochemical, genetic, thermodynamic, and autopoietic definitions given below. Metabolic Metabolic definitions are popular with biochemists and some biologists. Living systems are objects with definite boundaries, continually exchanging some materials with their surroundings but without altering their general properties, at least over some period of time. However, there are exceptions. There are frozen seeds and spores that remain, so far as is known, perfectly dormant. At low temperatures they lack metabolic activity for hundreds, perhaps thousands, of years but revive perfectly well upon being subjected to more clement conditions. A candle flame has a well-defined shape with a fixed boundary and is maintained by “metabolizing” its organic waxes and the surrounding molecular oxygen to produce carbon dioxide and water. Similar reactions, incidentally, occur in animals and plants. Flames also have a well-known capacity for growth. These facts underscore the inadequacy of this metabolic definition, even as they suggest the indispensable role of energy transformation to living systems. (See metabolism.) Britannica Quiz Biology Bonanza Physiological Venus flytrap Physiological definitions of life are popular. Life is defined as any system capable of performing functions such as eating, metabolizing, excreting, breathing, moving, growing, reproducing, and responding to external stimuli. But many such properties are either present in machines that nobody is willing to call alive or absent from organisms, such as the dormant hard-covered seed of a tree, that everybody is willing to call alive. An automobile, for example, can be said to eat, metabolize, excrete, breathe, move, and be responsive to external stimuli. A visitor from another planet, judging from the enormous number of automobiles on Earth and the way in which cities and landscapes have been designed for the special benefit of motorcars, might well believe that automobiles are not only alive but are the dominant life-form on the planet. (See physiology.)
The undisputed king of the modern battlefield is the Avtomat Kalashnikova model 47, or AK-47. Extremely reliable, the AK-47 is plentiful on Third...
Read More »
TSA Officers must apply sufficient pressure in order to ensure detection of any prohibited items. The officer will describe the patdown procedure,...
Read More »
If you think of all the things you can't live without, what comes to mind? In terms of the essentials, there are a few which can't be overlooked —...
Read More »
But if you're lost and no one else knows where you are, you might be in it for the long haul. You could be out there for days before you are able...
Read More »
Map your trek through cities near water, such as San Francisco, New York, Boston, and Baltimore, which dominated our Mobility category. Most of...
Read More »
The USMC Scout Sniper School is widely regarded in the military as the finest sniper training program. The Marines offer a tremendous program that...
Read More »
Promotion
Promotion
Promotion
Promotion